Devices and methods for “thermoanalysis” are known from the prior art and have now become established worldwide, in particular for purposes of material characterisation. Polymers, pharmaceutical substances, textiles, metals, ceramics and other organic or inorganic materials, for example, can thus be analysed and characterised.
In “thermoanalysis” (or “thermal analysis”), a sample to be investigated is subjected by means of a temperature control device (e.g. electrical heating device) to a controlled temperature change, e.g. a pre-adjustable “temperature program”. The sample may be heated, cooled or held at a constant temperature.
Complying as precisely as possible with the temperature program usually requires that the sample temperature is continuously detected, for example is measured with a temperature measuring sensor, so that a detection or measurement signal representative of the sample temperature can be used for a control (e.g. PID control) of the sample temperature.
Moreover, during the controlled change in the sample temperature, at least one (further) signal characteristic of a (further) property of the sample is continuously detected and recorded together with the course of the sample temperature.
Thermoanalysis thus enables the investigation and characterisation of temperature-related changes in properties of a sample material, including processes triggered thermally in the sample.
It is understood that the term “continuously” used here in connection with a detection (e.g. measurement) of signals also includes a quasi-continuous detection, for example one taking place at relatively small time intervals (e.g. periodically).
Thermoanalytical methods can be specified more precisely depending on which further signal or which further signals (apart from the sample temperature) are detected during the controlled change in the sample temperature. Such special methods of thermoanalysis are also known from the prior art and do not therefore require further explanation here. The following methods are mentioned solely by way of example: differential thermoanalysis (DTA), differential calorimetry (DSC) or dynamic differential calorimetry (DDK), thermogravimetry (TG) or thermogravimetric analysis (TGA) and thermomechanical analysis (TMA).
TG or a “simultaneous thermal analysis” (STA), i.e. a combination of TG and DSC or DDK, is often used for the characterisation of thermal vaporisation and decomposition effects. In a further development, apart from the detection of a loss of mass of the sample, an investigation of gases that are liberated by the sample can for example also take place. For the gas investigation, use can be made for example of Fourier transform infrared spectrometry (FTIR) or mass spectrometry (MS, for example using a quadrupole mass spectrometer).
The previously described measurement devices are generally characterised by a not inconsiderable size. The combination of two or more measurement devices and/or measurement methods is thus associated with a not inconsiderable requirement for space and equipment. The problem underlying the invention, therefore, is to create a compact measurement device, wherein an infrared spectrometer is efficiently and economically connected to a thermoanalytical measurement device.
In particular, the following publications are known from the prior art:
German patent application DE 100 52 511 A1 discloses a method and a device for evaluating chemical reaction processes. The described invention relates to a system for monitoring chemical reaction processes, in particular for detecting exothermic chemical reaction processes, and the use of such a system or a thermal radiation-sensitive sensor device, as well as a method for monitoring a plurality of chemical reaction mixtures. Furthermore, the disclosed invention relates to the area of combinatorial chemistry, in particular a method and a device for the monitoring and, if appropriate, control of exothermic reaction processes, preferably in so-called screening methods. The detection and evaluation of the measurement data preferably takes place by means of the sensor device and an associated evaluation device. Optionally, however, the evaluation can also take place in part or completely in the sensor device. The sensor device or its IR camera delivers measurement signals depending on the detected thermal radiation, said measurement signals being processed by the evaluation, in particular taking account of the temporal course or sequence. The processed signals, which for example represent the temporal course of the exothermicity or the temperature of the individual reaction mixtures, can preferably be displayed, printed out and/or outputted for further processing or storage, for example via a standardised interface or suchlike.
U.S. Pat. No. 4,914,297 shows an interface unit for a thermogravimetric analysis flow cell. The analysis flow cell comprises an elongated tubular cell body and an inlet and outlet made of glass for the flow of a gas. Furthermore, the device comprises a window element, which is permeable to infrared radiation, so that IR radiation can enter into and exit from the cell body. In addition, a mirror element is present for reflecting the IR radiation. The mirror element and the window element are mounted on the cell body in such a way that the overall unit can be quickly dismantled and reassembled.
Another German patent application, DE 100 01 382 A1, discloses an integral construction with a downstream opening section of a first furnace pipe, which is connected to a side face of a second cylindrical furnace pipe. The patent application also discloses a light transmission window, which is provided in the opening sections at the respective ends of a second furnace pipe, as well as a gas discharge section, which is disposed at least at one position in the side face of the second furnace pipe.
DE 199 34 448 A1 describes a method for performing differential thermoanalysis, which considerably reduces the equipment expenditure for the measurement by the fact that, compared to the previously known methods, the measurement and evaluation by means of only one measuring device is required, and which detects the heat of reaction alongside a signal type different from the heat of reaction. The invention is characterised in that a sample is heated/cooled according to a temperature program, during the heating/cooling the sample temperature is measured and stored, the mean heating rate beta is calculated from the stored values according to an equation and the difference between the stored values of the sample temperature and the temperature calculated from mean heating rate beta by means of an equation 2 is then determined.